Trouble Parsing XML using Go

Question

I've been trying to parse an xml in Go by defining structs and using xml.Unmarshal like this:

type InitiateResponse struct {
    SoapenvEnvelope struct {
        SoapenvBody struct {
            ReqResponseMsg struct {
                CData struct {
                    Response struct {
                        ResponseCode string `xml:"ResponseCode"`
                        ConversationID string `xml:"ConversationID"`
                        ResponseDesc string `xml:"ResponseDesc"`
                        OriginatorConversationID string `xml:"OriginatorConversationID"`
                        ServiceStatus string `xml:"ServiceStatus"`
                    } `xml:"req:Response"`
                } `xml: ![CDATA[`
            } `xml:"req:ResponseMsg"`
        } `xml:"soapenv:Body"`
    } `xml:"soapenv:Envelope"`
}   

var unit InitiateResponse
if err := xml.Unmarshal([]byte(data), &unit); err != nil {
    fmt.Println(err)
    return
}

There's no error thrown but the struct is always empty at the end. Can't understand why.

This is the xml:

<?xml version='1.0' encoding='UTF-8'?><soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:req="http://cps.huawei.com/cpsinterface/request">
   <soapenv:Header />
   <soapenv:Body>
      <req:ResponseMsg><![CDATA[<?xml version="1.0" encoding="UTF-8"?><Response><ResponseCode>14</ResponseCode><ConversationID>AG_20170222_000040cdc5cecf730e39</ConversationID><ResponseDesc>The caller information is invalid.</ResponseDesc><OriginatorConversationID>S_X2013012921001</OriginatorConversationID><ServiceStatus>2</ServiceStatus></Response>]]></req:ResponseMsg>
   </soapenv:Body>
</soapenv:Envelope>

Check it out: https://play.golang.org/p/Irmy8AsUKa

Your code is missing a print(err) at the end, which will tell you more about the error. — Roland Illig
– Roland Illig, Commented Feb 22, 2017 at 6:22
didn't include it here but there's no err. It parses successfully but the struct remains empty. — Jarri Abidi
– Jarri Abidi, Commented Feb 22, 2017 at 6:23

Sarath Sadasivan Pillai · Accepted Answer · 2017-02-22 09:36:03Z

4

CDATA can not be unmarshalled to a struct.

If the XML element contains character data, that data is accumulated in the first struct field that has tag ",chardata". The struct field may have type []byte or string. If there is no such field, the character data is discarded.

An attempt to unmarshal CDATA to struct will fail with following error

cannot unmarshal into struct

This playground link explains the above mentioned problem.

There were some other issues with the struct.Go currently does not support XML namespace prefixes .Here is an open issue regarding the same https://github.com/golang/go/issues/9519.

Here is code re-written

Code

package main

import (
    "encoding/xml"
    "fmt"
)

const data = `<soapenv:Envelope>
    <soapenv:Body>
        <req:ResponseMsg>
        <name>blah</name>
            <![CDATA[<?xml version="1.0" encoding="UTF-8"?><Response><ResponseCode>14</ResponseCode><ConversationID>AG_20170222_00006f8794f700eff099</ConversationID><ResponseDesc>The caller information is invalid.</ResponseDesc><OriginatorConversationID>S_X2013012921001</OriginatorConversationID><ServiceStatus>2</ServiceStatus></Response>]]>
        </req:ResponseMsg>
    </soapenv:Body>
</soapenv:Envelope>`

type Envelop struct {
    XMLName     xml.Name `xml:"Envelope"`
    ResponseMsg struct {
        CDATA []byte `xml:",cdata"`
    } `xml:"Body>ResponseMsg"`
}

type Response struct {
    XMLName                  xml.Name `xml:"Response"`
    ResponseCode             string   `xml:"ResponseCode"`
    ConversationID           string   `xml:"ConversationID"`
    ResponseDesc             string   `xml:"ResponseDesc"`
    OriginatorConversationID string   `xml:"OriginatorConversationID"`
    ServiceStatus            string   `xml:"ServiceStatus"`
}

func main() {
    var unit Envelop
    if err := xml.Unmarshal([]byte(data), &unit); err != nil {
        fmt.Println(err)
        return
    }
    responseBytes := unit.ResponseMsg.CDATA
    var response Response
    if err := xml.Unmarshal([]byte(responseBytes), &response); err != nil {
        fmt.Println(err)
        return
    }
    fmt.Println("Response : ", response)

}

Here is the play link : play.golang

edited Feb 22, 2017 at 9:36

answered Feb 22, 2017 at 9:18

Sarath Sadasivan Pillai

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2 Comments

Jarri Abidi Over a year ago

Thanks a lot! I had given up and had to resort to converting the xml to json to make it work. :D Really appreciate it.

Sarath Sadasivan Pillai Over a year ago

@JarriAbidi happy to help

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